Maya Problems and Solutions

ERROR: “unknown ref node”
SOLUTION:
maya.cmds.delete('_UNKNOWN_REF_NODE_')
File>OptimizeSceneSize is a 'Delete Unknown Nodes' 

ERROR: Error: [driver_exr] defaultArnoldDriver@driver_exr.RGBA: can’t create file “.exr”:
SOLUTION:
Make sure there is no “/” in front of your “File name Prefix”